Fluorescent glow sheet and the method of manufacturing the same



April 25, 1944. A R RUSSELL l 2,347,285

FLUORESCENT GLOW SHEET AND THE METHOD OF MANUFACTURINGTHE SAME Filed Mayl5, 1942 E /D\ INVENTOR.

Patented Apr. 25, 1944 FLUOBESCENT GLOW SHEET AND THE METHOD OFMANUFACTURING THE SAME Alfred R. Russell, Grosse Pointe, Mich., assignor.to The Burkhardt Company, a corporation of Michigan Application May 15,1942, Serial No. 443,160

4 Claims.

This invention relates to improvements in fluorescent glow sheets anddeals with improved graphic art methods of manufacturing glow sheets,bombardier charts, dials, computers, and the like from paper and plasticstock.

There have been a number of developments in the manufacture offluorescent, phosphorescent and luminous pigments, however, it hasheretofore been impractical to use these coarse crystalline pigments inthe graphic art industries because of the loss of luminosity life whenmixed with the usual varnishes and carrying agents employed in theprinting industry and in printing inks.

Inorganic fluorescent pigments of the zinc sulphide and cadmium sulphideclass which are considered preferable by the applicant in practicing theinvention consist of hard crystals of relatively large size and heavy inweight which properties prevent them from remaining in suspension anddispersion in printing inks.

The war has brought about a large demand for fluorescent glow sheets,bombardier charts, dials, computers, and the like, the copy and outlinesof which become visible responsive to ultra violet ray activation. Tomeet the large demand for highly efficient and effective fluorescentproducts, the applicant herein has developed and improved ultra violetray responsive glow sheets, bombardier charts, dials, computers, and thelike, and has developed and improved the methods of manufacturing thesame, largely employing graphic arts methods and equipment.

One object of the invention is to provide improved fluorescent paper andplastic products such as glow sheets, bombardier charts, dials,computers, and the like wherein the fluorescent copy isultra violet rayresponsive and will not readily deteriorate, and upon which productsnotations may be penciled and erased without destruction of thefluorescent copy.

Another object of the invention is to provide a simple, effective andeconomical method of manufacturing fluorescent paper and plastic ultraviolet ray responsive products of the type hereinbefore mentioned whichassures the highest quality and permanency of the products.

Other objects of the invention will become apparent by reference to thefollowing detailed description taken in connection with the accompanyingdrawing, in which:

Fig. 1 is a greatly enlarged cross sectional view through a paperfluorescent glow sheet embodying the invention manufactured inaccordance with my improved method.

Fig. la is an enlarged, fragmentary sectional view taken through a glowsheet similar to that shown in Fig. 1 but provided with an additionalouter roughened coating;

Fig. 2 is a greatly enlarged cross sectional view through a plastic glowsheet embodying the invention manufactured in accordance with myimproved method. l

Fig. 2a is an enlarged, fragmentary sectional view taken through aglowsheet similar to that shown in Fig, 2 but provided with an additionalouter rough coating;

Fig. 3 is a greatly enlarged cross sectional view through a paperfluorescent glow sheet embodying the invention manufactured by amodified improved method.

Fig. 3a is an enlarged, fragmentary sectional view taken through a glowsheet similar to that shown in Fig. 3 but provided with an additionalouter rough coating; and,

Fig. 4 is a fragmentary, sectional view of a construction such as thatshown in Fig.. 2 in which a roughened thermo-plastic sheet is employedin place of the final film 21 of the construction shown in Fig. 2.

Referring now to the drawing wherein like numerals refer to like andcorresponding parts throughout the several views, Fig. 1 shows a.fluorescent glow sheet embodying the invention composed of a paper stockbase sheet I0 which is rst sprayed or roll coated with an ethylcellulose, acrylic or methyl methacrylate lacquer coating or otherprotective film II which does not fluoresce under ultra violet rays andwhich will bar chemical reaction between the paper base and the laterapplied fluorescent material. After this protective coating l I isallowed to dry, the sheet I0 is then printed with a white opaque orclear pyroxylin ink or other suitable ink I2 compatible with theprotective coating II, and while the ink I2 is still wet or tacky,fluorescent pigment preferably of the zinc sulphide or cadmium sulphidetype I3 is dusted over the sheet. The said ink I2 is then allowed to dryand excess fluorescent pigment I3 which does not adhere to the said inkI2 is reclaimed. A protective film III preferably of ethyl cellulose,acrylic or methyl methacrylate lacquer is then sprayed over the entiresheet, however, other lacquers which have high light transmissionqualities and which do not fluoresce under ultra violet rays can be usedin place of the ethyl cellulose, acrylic or methyl methacrylateprotective lacquer fllm I4.

If desired, a second printing of clear pyroxylin or other suitable clearink I5 compatible with the the uorescent pigment I3. While the latterlayer of clear ink I5 is still wet or tacky, fluorescent pizment I6 likeor similar to the fluorescent pigment I3 is dusted over the sheet. Whenthe said ink I5 becomes dry, excess fluorescent pigment I6 is reclaimed,and the entire sheet is then sprayed with a protective non-fluorescentclear lacquer coating I'l preferably ethyl cellulose, acrylic or methylmethacrylate lacquer or other lacquer having high light transmissionqualities.

It will be noted that whether or not a single or double layer offluorescent pigment is used, the fluorescent pigment becomes embedded inthe ink employed; the lacquer top coating providing protection to thefluorescent pigment from the elements, from oxidation, and from otherchemical deterioration. It has also been found that the protectivelacquer top coating serves as a preservative against ultra violetdeterioration of the iluorescent pigment employed.

In such charts, glow sheets, and the like, upon the fluorescent surfaceof which it is desired to write in lead pencil or ink and later erasesuch writing, it has been found that, as disclosed in Fig. la, a finalcoating Il of lacquer like or similar to and compatible with theprotective coating I4 or I1 sprayed on the protective coating I4 or Ilunder high pressure produces a toothed or rough surface firmly anchoredto and integral with the protective coating I4 or I1 which can bewritten upon in pencil and ink and erased without destroying theusability of the said charts or the like.

The embodiment of the invention disclosed in Fig. 2 is like and similarto the embodiment of the invention hereinbefore described and disclosedin Fig. l except that the base sheet is of a plastic sheet stock of suchmaterial as nitrocellulose, cellulose acetate, ethyl cellulose, methylmethacrylate, vinyl acetate, acrylic resin or the like which is debossedat 2I to the outline of the lettering or other copy thereon. 'Ihedebossed area is then printed with an opaque or clear pyroxylln ink orother suitable lnk 22 compatible with the plastic base stock, and whilethe said ink 22 is still wet or tacky, fluorescent pigment preferably ofthe zinc sulphide or cadmium sulphide type 23 is dusted over the sheet.The said ink 22 is allowed to dry and excess fluorescent pigment 23which does not adhere to the said ink 22 is reclaimed. A protectivecoating preferably of a clear lacquer 24 of a type compatible to thebase sheet 20 and having non-fluorescent qualities is then sprayed overthe entire sheet.

If desired, a second printing of clear pyroxylln ink or other suitableink 25 compatible with the protective coating 24 may be placed inregistry over the fluorescent pigment 23. While the second layer of ink25 is still wet or tacky, fluorescent pigment 26 like or similar to thefluorescent pigment 23 is dusted over the sheet. When the said ink 25becomes dry, excess fluorescent pigment 26 is reclaimed, and the entiresheet is then provided with a protective non-fluorescent spray coatingof clear lacquer or a laminated film 21 preferably of the same type asthe lacquer coating 24 and compatible therewith.

The properties of the finished plastic sheet disclosed in Fig. 2 arelike and similar to the properties hereinbefore set forth as theproperties of the finished paper sheet disclosed in Fig. 1. In suchcharts, glow sheets, and the like, upon the fluorescent surface of whichit is desired to write in lead pencil or ink and later erase suchwriting,

ilnal coating 28 of lacquer like and similar to and compatible with theprotective coating 24 or 2l sprayed on the protective coating 24 or 2lunder high pressure produces a toothed or rough surfaceiilrmly anchoredto and integral with the protecti`ve coating 24 or 2l which can bewritten upon in pencil and ink and erased without destroying theusability of the said charts or the like.

A third embodiment of the invention is shown in Fig. 3 which disclosesa. fluorescent glow sheet composed of a paper stock base sheet 30 overwhich a roll coat or spray coat of ethyl cellulose, acroloid or methylmethacrylate lacquer or other protective film 3| is applied to barchemical reaction between the paper base and the later appliedfluorescent material. It is essential that the protective film 3| doesnot fluoresce under ultra violet rays. After the protective coating 3|becomes dried, a layer 32 of lacquer not incompatible with the coating3I having a fluorescent pigment preferably of the zinc sulphide orcalcium sulphide type dispersed therethrough is either sprayed or rollcoated over the coating 3I and allowed to dry. The background of thesheet is then printed with an opaque pyroxylln or other ink 33compatible with the layer 32, and lastly, a clear coating of ethylcellulose, acrylic or methyl methacrylate lacquer or other sprayed, rollcoated or laminated protective film 34 which does not fluoresce underultra violet rays and which has high light transmission qualities. Theprinting of the background 33 leaves the uorescent lettering and copy 35to show through the surface of the sheet.

If it is desired to write in pencil or ink upon the fluorescent surfaceof the sheet disclosed in Fig. 3,

and later erase such writing, it has been found, as disclosed in Fig.3a, that a final coating 38 of lacquer like and similar to andcompatible with the protective coating 34 sprayed on the protectivecoating 34 under high pressure produces a toothed or rough surfacefirmly anchored to and integral with the protective coating 34.

In the embodiments of the invention disclosed in Figs. 2 and 3, therough or toothed final writing surface may be accomplished by laminatingon top of the product in place of the protective coatings 2l and 34respectively a thin transparent thermoplastic film using a mat or finelyroughened embossing plate in the upper portion of the laminating press.Such a construction is illustrated in Fig. 4 as applied to amodification of the construction shown in Fig. 2, the roughenedthermo-plastic lm being indicated at 29.

With the exception of the above mentioned thermoplastic film which maybe laminated to the glow sheets disclosed in Figs. 2 and 3, all coatingsand ink employed are classed broadly as siccative coatings or inks andare selected for the particular properties herein defined which dryeither from evaporation, oxidation, crystallization or polymerization.The term "compatible" is employed herein to designate that the coatingor ink is not chemically deleterious to the adjacent ink or coating andwill not destroy the siccative qualities thereof. l

Like in the otherembodiments of the invention, the fluorescent crystalsbecome embedded in the pyroxylln or other ink employed and are coveredby a protective top coating which prevents the fluorescent crystals frombecoming oxidized or otherwise deteriorating. The protective top coatingalso provides a preservative against ultra violet deterioration of thefluorescent pigment employed.

'I'he methods employed are adaptable to autoit has been found, asdisclosed in Fig. 2G, that a 73 matic equipment of the graphic artsindustry, and,

it has been found that the applicant's products are superior in qualityand provide maximum brilliance under both visible light and ultra violetradiation with a minimum of loss of luminosity life. Also, whereiiuorescent pigments have been specified, it is'understood and it isobvious that phosphorescent or radio active pigments may be substituted.

Although but several embodiments ofthe invention and methods ofpracticing the same have been disclosedherein in detail, it is obviousthat many variations in the method steps and in the selection ofequivalent materials, pigments, lacquers and the like may be made inpracticing the invention without departing from the spirit and scopethereof as defined by the appended claims.

Iclaim:

1. A glow sheet comprising a plastic sheet debossed to the form of copyto be applied thereon, copy applied to said debossed portions of saidsheet comprising ink compatible with said plastic sheet, a layer offluorescent pigment on said copy, a protective illm over the entiresheet composed of a siccative material nonuorescent under ultra violetrays having high light transmission qualities and compatible with theink employed, a second copy layer comprising a clear ink having highlight transmission qualities compatible 'with the last-named protectivefilm disposed thereover in registry with the under copy, a layer offluorescent pigment on said second copy layer, and a ilnal protectivefilm over the entire sheet of siccative material non-fluorescent underultra violet rays having highlight transmission qualities and compatiblewith the ink employed.

2. 1A glow sheet comprising a base having a face non-nuorescent underultra violet rays and non-responsive to the eiects of later appliediluorescent pigment. copy applied to said face comprising an inkcompatible with the material from f which said face is formed,fluorescent pigment adhered to said copy, a protective illm over theentire base and said copy and pigment thereon composed of siccativematerial non-fluorescent under ultra violet rays having high lighttransmission qualities and compatible with said ink. a second copy layerco-extensive with the ilrst mentioned copy and comprising a transparentinkI having high light transmission qualities compatible with the lastnamed protective nlm disposed over said last named nlm in registry withthe ilrst mentioned copy. a layer of fluorescent pigment on said secondcopy layer, and an additional protective nlm of siccative materialnoniiuorescent under ultra violet rays having high light transmittingqualities and compatible with the ink employed disposed over said secondcopy layer.

3. A glow sheet comprising a base having a face non-iiuorescent underultra violet rays and nonresponsive to the effects of later appliedfluorescent pigment, copy applied to said face comprising an inkcompatible with the material from which said face is formed, fluorescentpigment adhered to said copy, a protective film over the entire base andsaid copy and pigment thereon composed of siccative materia1non-fluorescent under ultra violet rays having high light transmissionqualities and compatible with said ink, a second copy layer coextensivewith the first mentioned copy and comprising a. transparent ink havinghigh light transmission qualities compatible with the last namedprotective iilm disposed over said last named illm in registry with thefirst mentioned copyl a layer of fluorescent pigment on said second copylayer, an additional protective iili of siccative materialnon-iluorescent under ultra violet rays having high light transmittingqualities and compatible with the ink employed disposed over said secondcopy layer, and a transparent coating of material non-responsive toultra violet rays and compatible with said film and having a roughenedouter face applied over said lm.

4. A glow sheet comprising a paper base, a protective face over saidpaper base comprising a lm of siccative material non-iluorescent underultra violet rays and non-responsive to the effects of later appliedfluorescent pigment, copy applied to said face comprising an inkcompatible with the materia1 from which said face is formed, iiuorescentpigment adhered to said copy, a protective illm over the entire base andsaid copy and pigment thereon composed 'of siccative materia1nonnuorescent under ultra violet rays having high light transmissionqualities and compatible with said ink, a second copy layer coextensivewith the rst mentioned copy and comprising a transparent ink having highlight transmission qualities compatible with the last named protectiveiilm disposed over said last named nlm in registry with the firstmentioned copy. a layer or iluorescent pigment on said second copylayer, and an additional protective iilm of siccative materialnonfiuorescent under ultra violet rays having high light transmittingqualities and compatible with the ink employed disposed over said secondcopy layer.

ALFRED R. RUSSELL.

